Photographic camera



Sept. 29, 194-". K. PRITSCHOW PHOTOGRAPHIC CAMERA Filed Jan. 12, 1938 2 Sheets-Sheet l 'r i EE In venfar':

Afforney Sept. 29, 1942. K. Pm'TscHow PHOTOGRAPHIG CAMERA 2 SheeCs-Sheet 2 Filed Jan. 12, 1939 Inventor: I 1 M by l Ahomey Patented Sept. 29, 1942 PHOTOGRAPHIC CAMERA Karl Pritschow, Brunswick, Germany, assignor, by mesne assignments, to Sherka Chemical Co. Inc., Bloomfield, N. J., a corporation Application January 12, 1939, Serial No. 250,540 In Germany November 2, 1936 3 Claims.

My invention relates to improvements in photographic cameras, and more particularly in cameras provided with a table showing the depths of definition or the ranges within which objects are sharply reproduced on the sensitized surface for given distances of the objects and lens apertures. The object of the improvements is to provide a camera of this type in which the values showing the said ranges may be readily read while the photograph is being taken or the camera is set in position by means of the view finder. With this object in view my invention consists in placing the said table in such a position that it can be read while the image is being set on the focussing screen of the view finder. Thus, where the finder is arranged so as to be inspected from above the said table is arranged at the top part of the camera and with its surface directed upwardly. In cameras now in use the values indicating the depths of definition are disposed in several columns and lines, and therefore it is difflcult to find the correct value. In my improved camera the table is arranged so that only a single line is visible at a time,

' the values of each line corresponding to a definite range of the object and to the different lens apertures. In a practical embodiment the lines of the table are arranged on the side faces of a rotatably mounted polygonal drum which are selectively brought into the position in which they can be inspected, or on an endless band the lines of which are successively brought into position at the rear of a slot. The mechanism for moving the said drum or endless band is preferably connected with the mechanism for setting the object lens for focussing.

For the purpose of explaining the invention several examples embodying the same have been shown in the accompanying drawings in which the same reference characters have been used in all the views to indicate corresponding parts. In said drawings,

Fig. l is a sectional elevation showing a camera having a view finder arranged above the ex- .posure chamber and provided with a polygonal drum having the lines of the table of the depths of definition printed on its side faces, the said drum being located below the object lens of I cated above the object lens of the finder and immediately below the front part of the field lens thereof,

Fig. 4' is a sectional plan view taken on the line 4-4 of Fig. 3, I

Fig. 5 is a fragmentary sectional elevation showing the top part of a camera similar to the' one illustrated in Figs. 1 and 2, the said table being provided on an endless band located below the finder,

Fig. 6 is a fragmentary sectional elevation similar to the one illustrated in Fig. 5 and showing modification in which the endless band is located above the object lens of the view finder, and

Fig. '7 is a top plan view of Fig. 6.

Referring at first to the example shown in Figs. 1 and 2, the camera comprises a body I having an exposure chamber 2, an object lens 8, and a finder chamber 3 having an object lens 4 and a field lens 6. The sensitized film is wound on spools 9 and ill. The finder chamber is provided with an angularly disposed rear wall i3 having a mirror 5 mounted; thereon, the said mirror being adapted to direct the rays passing through the object lens 4 upwardly and through the fields lens 6. While the camera is out of use the said lens is protected by the side walls I of the hood folded thereon. At the bottom end of the inclined rear wall i3 the finder chamher is provided with a transverse slot l4, and below the said slot a polygonal drum I5 is mounted in the side walls of the camera casing I, the said polygonal drum having a table l6 having the ranges of sharp reproduction or depths of definition printed on its side faces. At one end the shaft of the said drum carries a milled disk l! by means of which the drum may be rotated for setting one of the side faces into position below the slot 14, a leaf spring l8 being provided for holding the drum in the set positions. Preferably the drum i5 is connected withthe focussing mechanism of the object lens 8, and as shown the said mechanism comprises a train of gear wheels IS, a worm 20 and a worm gearing 2! formed with internal screw threads engaging a sleeve 8! connected with the lens tube. Mechanism for thus shifting the object lens 8 in axial direction is known in the art, and I deem it not necessary to describe the same in detail.

Fig. 2 shows two lines of figures of the table IE printed on one of the side faces of the drum i5, and it will be understood that the other side faces have similar lines printed thereon, each corresponding to a particular range to which the object lens has been set. Thus the side face shown in Fig. 2 has the value m8 printed on its first or left hand column, the said figures indicating the range of the object which is 8 meters. In the next columns the lens aperture 126.3 has been indicated, and below the said indictaion the range of definition has been indicated, the figures 5.5 to 14 indicating that if the lens has been set to a range of 8 meters and the lens aperture is 1:6.3, a suificiently sharp image is produced when the distance of the obiect is not less than 5.5 meters and not more than 14 meters. In a similar way the lens aper tures 1:9, 1: 18, 1 25 and the corresponding ranges 4.8-22, 3.5'- and 2.9-- have been printed in the following columns. In a similar way on the other sides of the polygon the lines of the tables corresponding to other ranges have ben printed.

In the practical use of the camera the object lens is set by means of the milled disk ill in accordance with the distance of the object. Thereby the line of the table corresponding to the said distance and indicating the same in its left hand column, for example the line carrying the indication m8, appears in the slot id. the

polygon being'held in this position by the spring 88. .Now the camera is directed towards the obicct, and the said object is viewed through the view finder. From the construction shown in Fig. i it will be understood that the image ap= pears sharp inthe finder independently of the distance of the object. Wlnle the photographer directs the finder towards the object he is able to read the indications on the uppermost side 66 of the polygon id. The said indications are read through the lens 6, and therefore the figures appear enlarged.

In Figs. 3 and s the construction of the cam-- era is the same as has been described with reference to Figs. 1 and 2, and the same reference characters have been used to indicate corresponding parts. The drum carrying the table is mounted above the object lens Q- of the finder and immediately below the front end of the field lens d. Its shaft carries a milled disk 2?, and it is held in set position by a spring 28. The drum is connected with the mechanism for setting the object lens dthrough a bevel gear so, a spindle 35, a bevel gear 32, a spur gear and a spur gear 35 meshing with gear teeth provided on the lens tube. Thus the drum 255 may be rotated either by means of the milled dish 27 or by rotating the lens tube 3.

In the modification shown in Fig. 5 the table it is mounted on an endless tape 12 located below the slot it and the object lens l of the view finder, the saidtape being trained on rollers 53 and it mounted in the side walls of the camera casing l. The axle of the roller 33 carries a milled disk t: by means of which the line of the table corresponding to the distance of the object is brought into position below the slot it.

In the construction shown in the figure the rollers 33, so are not connected with the mechmsw. for setting the object lens 3, and therefore the table is set into position independently of the said object lens. But I wish it to be understood that my invention is not limited to this feature and that mechanism similar to the one shown in Fig. 1 or Fig. 3 may be provided for connecting the roller 43 with the setting mechanism of the object lens.

In Figs. 6 and 7 I have shown another modification in which the endless tape 52 on which the table I6 is printed is located above the lens 4 and immediately below the field lens 6. As shown the said tape is trained on rollers 53, 54 and 55, and the shafts of the rollers are mounted in the side walls of the camera casing I, while the shaft of the roller 55 is mounted on arms Ii pivotally mounted in the side walls of the I camera. casing at 56. One of the pivot bolts 56 carries a milled disk 51 by means of which the arm 5! may be turned to the left in Fig. '6 for; removing the tape 52 away from the field lens movement.

enemas 6. For fixing the arms 50 position a spring pressed pin 58 is slidably mounted in the side wall of the camera casing. The tape 52 is toramin-ated at-both ends as is shown at 59, and the said foraminated portions are engaged by prongs St carried by the roller 54.

The operation of the apparatus shown in Figs. 6 and Kids similar to the one described with reference to Figs. 1 and 2, the tape being set with one of its lines, for example the line m l in op" erative position, by' means of the milled disk ll.

Also in the construction illustrated in Figs. 6 and 7 the tape 52 is not shown to be connected with the mechanism for setting the object glass 8. But I wish it to be understood that my invention is, not limited to this feature.

In the construction shown in Figs. 6 and 7 only one of the pair of lines of the table corresponding to the ranges has been printed on thetape, and the line containing the letter m and the lens apertures is printed one. cleat 'ti fixed to the top of the body 5.

I claim:

1. In e. photographic camera comprising a eas ing having an exposure chamber and a finder chamber located above said exposure chamber, said finder chamber being provided with an object lens, a mirror in position for reflecting rays passing through said; object lens upwardly, and a field lens above said mirror, the invention herein described which consists of a movable carrier having a table showing depths of definition printed thereon. said carrier being located within the finder chamber adjacent the pencil of rays passing from said object lens of the finder towards said mirror and in position for permitting inspection of -one of its lines at a time through said field lens, and means for moving said carrier with any one of its lines into position permitting inspection through said field lens.

2. In a photographic camera, comprising a casing having an exposure chamber and a finder chamber located above said exposure chamber, said finder chamber being provided with an object lens, a mirror in position for reflecting rays passing through said object lens upwardly, and a. field lens above said mirror, the invention herein described which consists of a movable carrier having a table showing depths of definition printed thereon, said carrier being located above the penoil of rays passing from said object lens of the finder towards said mirror and in position for permitting inspection of one of its lines at a time through said field lens, and means for moving said carrier with any one of its lines into position permitting inspection through said field lens.

3. In a. photographic camera. comprising a casing having an exposure chamber and a finder chamber located above said exposure chamber, said finder chamber being provided with an object lens, a mirror in position for reflecting rays passing through said object lens upwardly, and a field lens above said mirror, the invention herein described which consists of a depth of focus indicator that includes a slot in the wall of the finder chamber at the lower edge of said mirror and a carrier movable beneath and transversely of such slot, said carrier being provided with a succession of lines of data extending line after line in a direction transverse to the direction of carrier KARL PRITSCHOW. 

